Intensity control system for cathode ray beams



De -28, 1937. M VON ARDENNE 2,103,652

INTENSITY CONTROL SYSTEM FOR CATHODE RAY BEAMS Filed 001;. 24, 1936 Patented Dec. 28, 1937 UNITED STATES PATENT OFFICE INTENSITY CONTROL SYSTEM FOR CATH- ODE RAY BEAMS Manfred von Ardenne, Berlin, Germany 3 Claims.

This invention relates to means for controlling the intensity of the cathode beam in Braun tubes.

It has already been proposed to employ for the beam intensity control of Braun tubes a plate situated in the immediate vicinity of the cathode and arranged inside the Wehnelt cylinder itself. This sort of control certainly results in an increase in the sensitiveness, but at the same time appears to cause a slight variation in the concentration of the beam.

The object of this invention is to provide an arrangement which allows of an increase in the sensitiveness of the intensity control with a particularly slight effect on the position and concentration of the beam.

According to the invention, the intensity control A, C. potential is applied simultaneously cophasal or in phase opposition to the Wehnelt cylinder and a control electrode located in the interior of the Wehnelt cylinder. The two control eiTects support each other, as they act on the ray current in the same sense.

A form of embodiment of the arrangement according to the invention is illustrated by way of example in the drawing, the single figure of which shows diagrammatically a Braun tube and its electrode system as well as certain circuits associated therewith.

In the figure, I is the wall of the tube, 2 the cathode, 3 the Wehnelt cylinder, and 4 the control electrode. The control potential, which is indicated in symbolical fashion by the generator 5, is conducted over the condensers 'l, the value of each of which may be 0, 1 mf., simultaneously to the control plate 4 and the Wehnelt cylinder 3. The resistances 6 and 9 may conveniently each be 10 ohms, and the potentiometer may be 5, 10 ohms.

The condenser 8 may possess a value of 0.5 mi. The Wehnelt cylinder may naturally be provided with a suitable negative bias.

I claim:

1. In combination 2, Braun tube for television purposes comprising means including a cathode for producing a cathode beam, a Wehnelt cylinder surrounding said cathode, and a perforated plate 10 mounted inside said Wehnelt cylinder, means to supply said Wehnelt cylinder with an adapted. initial potential and means for supplying both said Wehnelt cylinder and said perforated plate with a control voltage to control the intensity 15 of said cathode beam.

2. In combination a Braun tube for television purposes comprising means including a cathode for producing a cathode beam, a Wehnelt cylinder surrounding said cathode, and a perforated plate 20 mounted inside said Wehnelt cylinder, means to supply said Wehnelt cylinder with an adapted initial potential and means for applying control voltages co-phasically to said Wehnelt cylinder and to said perforated plate to control the in- 5 tensity of said cathode beam.

3. In combination a Braun tube for television purposes comprising means including a cathode for producing a cathode beam, at Wehnelt cylinder surrounding said cathode, and a perforated 30 plate mounted inside said Wehnelt cylinder, means to supply said Wehnelt cylinder with an adapted initial potential, and means for applying control voltages in phase opposition to said Wehnelt cylinder and to said perforated plate 35 to control the intensity of said cathode beam.

MANFRED von ARDENNE. 

